An optical path network is known that transmits wavelength division multiplexing (WDM) light including a plurality of (M) wavebands each formed by combining lights of a plurality of, i.e., N, wavelengths respectively corresponding to a plurality of (N) wavelength channels (wave channels or light paths) divided by, for example, 100 GHz in a predetermined communication wavelength range via a plurality of (K) optical fibers in parallel. In each relay node of such an optical path network, wavelength division multiplexing lights respectively transmitted through the K optical fibers are subjected to route switching on the basis of a waveband or on the basis of a wavelength division multiplexing light group directly to an optical fiber in a predetermined transmission direction, and a wavelength (channel) included in the waveband is separated and dropped (output) to an electric layer as needed, or a waveband recombined into wavelength division multiplexing light including a wavelength channel acquired by converting a signal added from the electric layer into light is subjected to route switching to an optical fiber in a predetermined transmission direction. For example, this corresponds to an optical path cross-connect apparatus described in Patent Document 1.
It is desired to have a function enabling any wavelength channel in wavelength division multiplexing light in any input fiber to be dropped to a connection port to an arbitrary electric layer (electric level) EL and enabling an added wavelength channel to be allocated into an arbitrary wavelength division multiplexing light waveband between a wavelength level for transmission through optical paths and an electric level at the time of an optical signal termination process in a relay node of the optical path network, i.e., a colorless, directionless, and contentionless function.